This invention relates to a method for operating a vehicle monitoring system during a sleep mode.
Many modern vehicles are designed to enter a sleep mode after the vehicle has been inactive for a predetermined length of time. In the sleep mode, most of the vehicle subsystems are switched to an off or inactive state to eliminate any parasitic or dark current draw on the battery from the inactive subsystems.
In a vehicle, a parasitic current draw continuously drains a small amount of current, usually a few milliamps, from a battery when the engine is off and the battery is not being continuously charged. Reducing the parasitic current draw on the battery increases the life of the battery as well as the length of idle time during which the battery will remain charged.
Modern vehicles are typically equipped with a monitoring system which monitors subsystem inputs and actuates other subsystems, as appropriate. As an example, the monitoring system will typically monitor motion detectors for the door locks and other systems.
Some vehicle subsystems, such as the vehicle monitoring system, must remain in a semi-active state in the sleep mode to detect unauthorized entry into the vehicle or prevent unauthorized ignition of the engine. Also, the monitoring system wakes the vehicle when an operator unlocks a door or activates a door handle switch. To operate in a semi-active state during the sleep mode requires power or current from the battery. As a result, prior art vehicle monitoring systems typically place a parasitic current draw on the battery during the sleep mode. It would be desirable to reduce the amount of parasitic or dark current draw on the battery of the vehicle during the sleep mode.